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How to pour Babbitt bearings

When rebuilding an engine meant pouring molten metal

Story Earl Duty - May 01, 2011 09:00 AM

Many of us involved in the world of automotive engines (past and present) recognize these bearing inserts to be commonplace. Their makeup consists of a steel backing plate, an aluminum alloy with copper bonding on top of that and finally, a lead/tin/copper layer.

Kerry Buchenroth uses an acetylene torch to remove any and all old Babbitt from the engine block that is to be re-Babbitted.

In many cases, it’s also necessary to drill out old Babbitt from the block.

A product called Babbitrite is used to plug holes and keep excess poured Babbitt from sticking anywhere it shouldn’t.

The next step in our pouring process involves attaching a Babbitt dam to the block assembly.

Back in the old days, a generic test for proper Babbitt temperature was, if a piece of pinewood (after stirring the molten liquid) came out just a light gray, it was not hot enough. If it came out black it was good to pour. If the pinewood caught fire while stirring it was too hot.

With the Babbitt at the right temperature, the pouring of the new bearings begins.

After the pouring fixture has been removed, our block is ready for removal of the excess Babbitt and smoothing out to match the block surface. The main caps will be poured in a separate operation using a main cap fixture.

It is imperative that a form of flux (in this case TinTite) be used for proper adhesion of Babbitt to a rod or rod cap.

The rod, rod cap, and TinTite must also be pre-heated with a torch just prior to the pouring of the Babbitt.

Pouring of the rod Babbitt works much like the block by using a rod Babbitt dam.

If a rod or rod cap has not been properly fluxed, the Babbitt can separate from either, or both sections.

This align boring jig was designed and built by Bill Lucius and Joe Bell for not only align boring Model T engines, but with the addition of a few specialty adapters, Model A engines as well. As compressed air keeps everything cool, our main cap and block journal receives its finish cut.

Model T Reverse Pedal Extension: While at the Babbitt Bearing workshop, we noticed these pedal extensions, and anyone who has ever driven a three-pedal Model T can appreciate the value in this extension.

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In our modern world of automotive engineering, most of us can identify with main and rod bearings being referred to as inserts. They are comprised of two bearing halves (upper and lower) that simply insert into an engine block, connecting rod or rod cap.

References show that the Clevite Corporation (founded in 1919 as Cleveland Graphite Bronze) was manufacturing engine bearing inserts in 1929. Poured Babbitt bearings in Henry’s Model T were the norm, and Ford’s T is the focus of our poured bearing documentation. Until somewhere around the mid-’30s, poured Babbitt bearings were commonplace in automotive applications.

I’ve had an opportunity to attend a hands-on workshop demonstrating how to pour Babbitt bearings in Model T engines. This workshop was orchestrated by Kerry Buchenroth at his Lakeview, Ohio, old car shop, and demonstrated by Joe Bell of Engines by Joe.

It should also be noted that Bell does not rebuild Model T Babbitt-type engines as a full-time job, but does pour and bore engines for others upon request. Bell does this for the love of the hobby, and loves demonstrating to anyone interested in attending a workshop on the art of pouring Babbitt. Caution: do not attempt melting and pouring Babbitt without the proper knowledge, tools, equipment and safety gear!

First, a wee bit about Babbitt bearings: Babbitt metal is an anti-friction metal alloy first produced by Isaac Babbitt in 1839. And it has evolved through the years to provide a longer life span than the original Babbitt alloy. Bell uses a product called Power Nickel Babbitt which is also very close to Ford’s original recipe, and one 3½-pound ingot is typically enough for one engine.

Power Nickel Babbitt has a tin- based composition consisting of:

• Tin – 88 to 90 &perc;

• Copper – 3 to 4 &perc;

• Antimony – 7 to 8 &perc;

• Lead – 0.2 &perc; maximum

This Babbitt has been designed to withstand extremely heavy sustained loads, and high local heat conditions. It is alloyed for strength and hardness and will not squeeze out even under very heavy pressure, which makes it a perfect candidate for Model T engines. Other applications for this type Babbitt are marine reciprocating engines, water turbines, paper mill calendar stacks and rolling mill machinery.

Bell started our workshop by first giving a short history lesson on the poured Babbitt bearings prevalent in Model T engines. From there, it was on to proper align boring (setup and actual boring) of the finished (poured) block. Bell and Bill Lucius of New Reigel, Ohio, custom built their align boring fixture to fit not only the Model T, but also with a few added attachments, the Model A.

While the Power Nickel Babbitt was reaching optimum temperature in the melting pot, Bell had Kerry Buchenroth heat the main bearing surfaces of an old block with an acetylene torch to remove any and all remnants of old Babbitt. With the block void of any remaining Babbitt, a special fixture was then attached to the block to include pieces of machined steel referred to as Babbitt dams.

Buchenroth then re-heated not only the engine block but also all the attached fixtures. When the new Babbitt had reached a melted temperature of 700 degrees, Bell filled two ladles with Babbitt and proceeded to pour the hot metal into the bearing fixtures. The actual pouring process after block preparation took approximately two seconds per main bearing (there are three). It’s a quick and painless operation, assuming all safety precautions had been observed.

With the block mains poured, Bell proceeded to clean, flux, heat and attach both the connecting rod, and rod cap to a fixture referred to as a jig, designed just for rods and rod caps. The poured Babbitt bearings were kept as thin as possible, depending upon rod, rod cap, and main journal measurements.

According to Bell, thinner is better. In the days of the Model T, Ford was known to use shims that could be peeled off as the Babbitt wore. Ford was also known to use two .002-inch shims on each cap, and Babbitt that was a mixture of 86 percent tin, 7 percent copper, and 7 percent antimony. The poured Babbitt bearings commonly get somewhere around 40,000 to 50,000 miles of use (depending upon use and/or abuse) before needing replacement. Poured Babbitt bearings are also known to fail without much fanfare, therefore allowing the car to be driven for longer periods of time, even after bearing failure.

Due to its alloy composition, the failed bearing, in many cases, was not likely to damage the crankshaft.